Innovative Capability to Quantify Fatigue Damage and Assessment of Endurance Limit in Spectrum Load Histories

TDA will utilize the latest improvements in both testing and analytical techniques to reliably assess damage and hence life of structural components that experience divergent service loadings. The analytical formulations for quantifying damage will be tested and implemented in new continuum damage mechanics (CDM) models and current programs used by Navy such as FAMS and UNIGROW. These programs will be used to reliably assess the lfie of structural components, and to calculate times for initial and recurring inspection, overhaul times, and safe rework limits. The finite element implementation of the CDM model is a unique feature of this effort, which can be extended to non-metals also. Reliability calculations of structural components at long lives are expected to improve significantly due to the enhanced analytical formulation developed and supported by the critical test data generated in this effort. TDA"s end product resulting from this effort will be total life prediction software that will include modules for crack initiation and crack growth in both deterministic and probabilistic framework. The crack initiation module offers the choice of various modules, stress-life, strain-life, and CDM models. The crack growth module offers the UNIGROW portion for both short and long crack growth behavior. The unique feature of the TDA"s total life prediction software is that this module provides reliable life prediction for the unfiltered loading histories by calculating damage for cycles in VHCF regime considering load interaction effect. The probabilistic framework provides the necessary features and functions to conduct reliability analysis.